2. better - the best
3. young - the youngest
4. pretty - prettier
5. cheaper - the cheapest
7. expensive - the most expensive
8. more interesting - the most interesting
9. delicious - more delicious
10. more beautiful - the most beautiful

2. good => better => the best 
3.young => younger => the youngest
4.pretty => pretter => the pretties
5.cheap => cheaper => the cheapest
7.expensive => more expensive => the most expensive
8.interesting => more interesting => the most interesting
9.delicious => more delicious => the most delicious
10.beautiful => more beautiful => the most beautiful